And the possible interactions of L-arginine are (according to
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Anticoagulants and anti-platelet drugs, herbs and supplements. These types of drugs, herbs and supplements reduce blood clotting. Taking L-arginine with them might increase the risk of bleeding.
Blood pressure drugs, herbs and supplements. L-arginine might lower blood pressure in people who have high blood pressure. Combining use of L-arginine with a blood pressure drug, herb or supplement might increase the risk of blood pressure becoming too low.
Diabetes drugs, herbs and supplements. L-arginine might decrease blood sugar levels in people with diabetes. If you're taking diabetes drugs, herbs or supplements, your dosage might need to be adjusted.
Isoproterenol (Isuprel). Use of this heart medication with L-arginine might cause your blood pressure to become too low.
Nitrates. Use of this chest pain medication with L-arginine might cause your blood pressure to become too low.
Water pills (potassium-sparing diuretics). Don't take L-arginine with amiloride (Midamor), spironolactone (Aldactone, Carospir) or triamterene (Dyrenium). These medications can increase potassium levels, increasing the risk of developing a higher than normal level of potassium in your blood (hyperkalemia).
Sildenafil (Revatio, Viagra). Use of this erectile dysfunction medication with L-arginine might cause your blood pressure to become too low.
So these supplements can also be dangerous. They are effectively drugs, but not controlled by being a prescription only drug.
If 100 mg isn't working for the OP then a trip to the doctor is a must. The cause could be diet or other health related issue which should be checked out. Losing weight and improving general fitness might be part of the solution. Age may also be an issue.